1. Field of the Invention
The invention relates to a data cable with at least two conductors for differential signal transmission as well as a casing, in particular one made of an electrically insulating material, which surrounds the conductors.
2. Description of Related Art
During the transmission of the differential or symmetrical signals, identical data signals are transmitted via at least two conductors with opposite polarity. The two conductors of the cable are so designed that all inductive and capacitive interference affects these as identically as possible. The interference can then be eliminated through formation of the differential between the two signals.
It is known for cables to be used for data transmission in which four conductors are provided in a so-called star quad arrangement. Such a cable can provide two differential signal pairs, wherein the two conductors diagonally opposite one another in the star quad each faun a differential conductor pair. A significant advantage of the star quad arrangement is that each of the conductor pairs always lies in the virtual ground plane of the other conductor pair. This makes it possible to realize a high crosstalk attenuation while at the same time keeping the cable as compact as possible. The highest possible crosstalk attenuation is necessary in order to be able to transmit mutually independent broadband data streams on both conductor pairs without harmful mutual interference.
Current star quad cables reach their limits at data rates >2 GBit/s, as provided for, for example, in the USB 3.0 (USB: Universal Serial Bus) or MHL (Mobile High Definition Link) standard, in particular where long cable lengths are involved. In particular, mode conversion, crosstalk and cable attenuation all increase at higher frequencies.
The document DE 299 07 039 U1 discloses a data transmission cable with several insulated conductors, each with a closed metal sleeve on the surface of the conductor insulation. The conductors can be surrounded by an intermediate casing, a metal sleeve covering this and an outer casing.